Question
What is the role of silica in the extraction of copper?
Solution
Ores of copper contain iron oxide as an impurity. Silica reacts with iron oxide and forms iron silicate, which is removed as slag. In the smelting process such chemical reactions are taking place:
1) Oxidizing of the copper pyrite: 2 CuFeS2 (s) + 3 O2 (g) → 2 FeO (s) + 2 CuS (l) + 2 SO2 (g)
2) Conversion of iron oxides and sulfides into molten slag:
FeO (s) + SiO2 (s) → FeSiO3 (l)
2 FeS (s) + 3O2 (g) + 2 SiO2 (s) → 2 FeSiO3 (l) + 2SO2 (g)
